The present invention relates to a process employing a shaped supporting mold comprising a plurality of grooves for manufacturing shaped curved bars having a constant or non-constant cross section, made of a material reinforced with filaments, and to a unitized assembly comprising the supporting mold with at least two shaped curved bars.
The present invention also relates to a process and a device for facilitating installation of reinforcing bars in bodies comprising reinforcing sheeting, for bodies of revolution such as, for example, a flexible pipe whose sheeting is composed of a large number of reinforcing bars.
The present invention also relates to reinforced bodies comprising a reinforcing armature made with at least one elongated curved, shaped element reinforced with several bars, such as a supporting mold whereby the reinforced bodies can be lightweight, flexible, tight pipes having reinforcing armatures designed to withstand tractive forces and having a high degree of resistance as a result of helical winding of the shaped bars.
In for example, French patent A2 312,356, a shaping of reinforced plastic material is proposed wherein a filament mixture with a high resistance to tractive force, such as fibers of glass, carbon or organic material, and a cross-linkable plastic is added to a shaped groove forming a mold, with the shaped groove being wound on a wall of an mandrel or drum, and with the shaped element being extracted from the shaped groove after at least a partial cross-linking resulting, for example, from a heat treatment.
With the above-described proposed technique, during the production of shaped curved bars, the length of the bars produced by machine levels off rapidly because the rotational speed of the mandrel or drum is limited, primarily to reduce operating expense by using a classical impregnation technique.
In addition, the widths of the shaped curved bars that is, the dimension of the cross section along the perpendicular to the radius, with the thickness being defined as the dimension of the cross section in the direction of the radius, which in manufacturing determines the advance of the bar per turn on the mandrel, with the advance per turn being essentially equal to the width of the mold or rather the width of the bar plus the width or thickness of the radial wails of the mold directly affects the productivity of the manufacturing machine.
Thus, at a certain rotational speed such as, for example, a maximum rotational speed, or for a certain bar length production rate, the narrower the bar, the slower the rate of production of bar covering surface (the width of the bar multiplied by the length produced per unit time), and consequently the less the machine produces.
If several shaped curved bars are produced simultaneously on the same mandrel, the length of bar actually obtained is the same as the sum of the lengths of all the bars produced. Thus, production is multiplied by a factor essentially equal to the number of bars produced simultaneously, since the stabilization means such as heating can be adapted easily for such an increase in production without presenting any significant problems related to this increase and also knowing that in the case of very narrow shaped curved bars, these stabilization means are often sufficient.
This simultaneous production of several bars can be obtained by using a shaped and elongated supporting mold which comprises essentially parallel grooves running along the longitudinal axis to permit the bars to be molded at least to the cross section of the grooves, with at least one groove being partially fillable.
In addition, the use of a multi-groove supporting mold makes it possible to reduce the thickness of the supporting mold between the grooves relative to a sum of the two thicknesses of mold to a single groove, as described in French Patent A 2,312,356.
Thus, by reducing the width of the supporting mold, the cost of the mold, generally made of a heavy material can be reduced and the number of turns of the bars on the mandrel, particularly in a stabilization zone, can be increased.
Thus, at a given rotational speed of the mandrel or rate of covering surface production, by using a multi-groove mold, it is possible to have a stabilization time longer than a stabilization for manufacturing the same number of bars simply by joining several single-groove molds, with each single-groove mold shaping one bar.
On the other hand, if the shaped supporting mold which simultaneously produces several curved bars is made in one piece, this shaped supporting mold will act like a unitized assembly which is very easy to handle after the bars have been stabilized.
Stabilization is construed to be a physical or chemical process such as melting with cooling or cross-linking which allows a body referred to as stabilizable, to assume a stable form. Thermoplastic, thermosettable, or elastomeric materials, for example, are stabilizable bodies.
The multibar unitized assembly described above is particularly useful from the standpoint of storage and handling, since it is possible to reduce the number of storage reels by virtue of the fact that, unlike conventional proposals, it is not necessary to provide as many reels as curved bars. Moreover, entanglement of curved bars during handling, which a natural tendency of the curved bars, particularly in the manufacturing of all flexible tubing is avoided. This is especially valuable for manufacturing any elongated bodies, and, in particular, bodies of revolution, including numerous narrow bars, such as elongated shaped elements.
Moreover, the unitized assembly according to the invention, containing several bars nevertheless behaves as a single wide bar when stranding a flexible tube thereby making it possible to retain all of the advantages of wide bars and in certain cases to justify the use of a shaped supporting mold comprising a large number of narrow bars, that is bars having a height greater than a width thereof.
Thus French Patent A 2,210,266 and corresponding U.S. Pat. No. 4,013,100 demonstrate the value of the flexibility of reinforced flexible pipes and for reinforcing sheeting resistant to tractive effort obtained by using curved reinforcing bars whose moment of inertia of the cross section relative to an axis passing through its center of gravity and perpendicular to the radius of curvature is greater than all the other moments of inertia of the cross section relative to another axis passing through the center of gravity.
Such a requirement therefore means, for example when using shapes with a rectangular cross section, that the height of the curved bar, that is, the dimension of the cross section along a radius, must be greater than its width or dimension of the cross section along a perpendicular to the radius. However, since the thickness of the reinforcing sheeting or the height of the reinforcing bars is a given, this implies a reduction in the thickness of the bars comprising the sheeting, or an increase in their number.
Thus, increasing the number of bars or wires, when the reinforcing bars are laid to manufacture the body comprising the reinforcing sheeting results in an increase in the number of dispensing reels for these bars, in the material, and the adjustments.
If one attempts to place several wires side by side on the same reel, experience has shown that tangles result in a short time when unreeling. Moreover, it is necessary for the bars to be shaped very exactly and bent before laying in order to ensure the sitting of the bars without sagging.
The process and the device for laying reinforcing bars according to the present invention makes it possible in particular to preserve the advantages of using wires that are taller than they are wide, while avoiding the disadvantages associated with the laying of such wires.
The process and the device for laying reinforcing bars according to the present invention make it possible in particular to sheathe a tube using a conventional sheathing machine, without any expensive modification or the need for high precision regulation.
In general, an elongated shaped support which maintains the reinforcing bars parallel to one another and in the same orientation, is then used to produce a unitized assembly which is very easy to handle, allowing the bars to be wound onto the reels of the sheathing machine, unwound, and laid on the flexible elongated body with considerable ease and safety. The term orientation means that all the centers of curvature of the curved bars located on any cross section of the support will be on the same side of the support from either above or below.
The reinforcing bars can be assembled by the shaped support, for example, either when the reinforcing bars are being preshaped, or immediately afterwards if working with metal bars made, for example, of steel, or during the manufacture of the bars, for example, when the bars are made of a plastic material reinforced with filaments that have a high resistance to tractive effort.
In accordance with the present invention, the unitized assembly formed as described above is wound on a reel before being mounted on the sheathing machine thereby greatly facilitating the manufacturing process.
The process and device for laying of reinforcing bars in accordance with the present invention are particularly useful for manufacturing curved bars from a reinforced plastic since a number of the curved bars can be simultaneously manufactured in a one-piece mold which supports the curved bars for subsequent winding of the curved bars with reinforcing sheeting.
Thus, by virtue of the features of the present invention, it is possible to eliminate an additional step involving the laying of a support before winding thereby increasing the benefits associated with a mold which is simultaneously used to manufacture several bars.
The process of laying reinforcing bars according to the present invention includes using one or more unitized assemblies which are mounted on one reel or as many reels as are necessary for the sheeting machine, with the unitized assemblies being composed of reinforcing bars joined by the support mold. The assemblies are unreeled and laid in the same manner as a strip or wide shaped member is laid on a core of a pipe to be wrapped, and the support is withdrawn when the bars are no longer in danger of becoming entangled with one another.
With metal reinforcing bars, a supplementary operation is required, namely, assembling the bars on a shaped support with several grooves; however, the features of the present invention are very advantageous in certain cases for a number of bars to comprise a unitized assembly when they are laid. Thus, when many bars must be simultaneously wrapped, the number of reels on the winding machine can be considerably reduced.
More particularly, in the manufacture and use of bars made of reinforced plastic, but without the use of this type of support being limitative, the support can be shaped and elongated and comprise essentially parallel grooves and extend along the longitudinal axis to permit the bars to be molded at least to the groove's cross section and at least one groove can be partially filled. The support can be the supporting mold described above and serve for making the bars. In the same way as the multibar unitized assembly is used to install the reinforcing sheeting by means of a sheeting machine with recycling of the multi-groove supporting mold, the flexible tubing or elements comprising reinforcing bars made of reinforced composite materials can be made by using unitized elements such as the shaped supporting mold mentioned above, containing shaped curved bars.
The present invention also proposes an elongated body comprising at least one curved elongated shaped element reinforced with several reinforced curved bars. This multibar shaped element is used in a reinforcing sheeting and has a mechanical behavior at least as good as that of the bar assembly composing them and usable in assembling reinforcing sheeting for a reinforced body. This shaped element also offers a number of advantages over a set of bars used independently of one another.
These advantages include ease of manufacture, ease of handling for manufacturing reinforcing sheeting, and higher production rate, all of these elements being reflected in financial advantages to which may be added the possibility of obtaining anti-wear shapes using less antiabrasion material, and shapes using a type of sheeting which is less expensive than the shapes according to the prior art.
More specifically, the shape is composed, for example, of an elongated shaped supporting element with a constant or non-constant cross section comprising several grooves separated by walls and having the shape of a comb in cross section, and with several curved bars located inside said grooves.
The curved bars can be made, for example, of a stabilizable material and may contain reinforcing filaments resistant to tractive effort.
The profiled element is particularly applicable when used to manufacture bodies comprising reinforcing armatures such as sealed pipes, cables, and bodies of revolution.
To explain the invention in a non-limitative manner, a flexible pipe may be considered which comprises armatures resistant to pressure and/or traction forces, with the flexible pipe serving to convey a fluid such as, for example, a hydrocarbon. Flexible pipes of this type are generally subjected to significant tractive forces either when the flexible pipes are installed, especially, when laid on a seabed, or during use of the flexible pipes.
The flexible pipes which can be used for this purpose generally comprise a flexible tight tubular core which can be composed of an elastomer or plastic material, at least one pressure-resistant armature, and at least one armature resistant to tractive and/or torsional forces applied to the pipe, with the pipes also comprising one or more sealing sheaths.
The armatures are formed by helical windings or by rings, wires, strands, bars, or shapes of metal or reinforced cross-linkable material in a manner as described more fully in French Patents 2,312,356 and 2,283,768 corresponding to U.S. Pat. No. 3,966,388.
In the reinforcing sheeting which comprises the flexible pipes, the reinforcing bars have a certain degree of mobility with respect to one another, and the present invention makes it possible to retain the advantage associated with this relative mobility of the bars, but to eliminate the disadvantages.
If the bars are movable with respect to one another in the supporting element, and if this element is designed to be elastic, the bars will not be mechanically linked to one another and, in traction, torsion, and flexion, will exhibit behavior similar to that of the bars in the absence of the supporting element.
If the bars adhere to the supporting, element, the supporting element must be highly deformable and, if the bars are free to slide in the grooves in the supporting element, the supporting element must have less deformation.
The construction of the supporting element with less deformation is preferable since the supporting element is under less mechanical stress but may, in a manner described more fully hereinbelow, integrate one or more bars or surface areas of the bars with the supporting element to distribute wear over the surfaces in motion.
Preferably, according to the present invention the shape notably offers the advantage of being simple to produce when the supporting element is used to produce several reinforcing bars. This possibility of a dual purpose option only exists if the supporting element is simultaneously adapted for the requirements of sheeting used for reinforcing reinforced elongated bodies and the requirements associated with manufacturing curved bars reinforced with the composite material.
In general particularly when the supporting element is used as a mold for manufacturing bars, the supporting element will be referred to as a supporting mold.
Using the supporting element as a mold and support eliminates the unmolding process and cleaning operations such as eliminating dirt particularly, when using fiberglass. If it is desired to recycle the supporting mold. Moreover, it is easier to handle the shaped bars because the shaped bars are assembled into a unitized assembly which becomes more advantageous as the bars composing the assembly become narrower and hence more numerous. This in turn, makes it easier to wind the assembly, especially as the number of shapes to be laid simultaneously decreases, and when correctly used, does not impair the mechanical characteristics of the reinforced elongated bodies that comprise the assembly.
French Patent 2,210,266 provides an example of the advantage, for the stability of the sheeting, of making the traction-reinforcing sheeting of flexible tubing using shaped bars, whose moment of inertia of a cross section relative to a transverse axis passing through the center of gravity of the section is greater than that of the moments of inertia measured relative to other axes passing through the center of gravity or, in other words disposed on a pipe in such fashion that its radius passes through the center of gravity and is perpendicular to the transverse axis.
However, the manufacture and production of such pipes are generally very difficult due to the large number of shaped bars used, especially when shaped reinforcing bars having a rectangular cross section with a narrow width and a large height.
The present invention overcomes this disadvantage among others by proposing a unitized assembly or multi-bar shape which is easily laid (smaller number, fatter shape), which behaves in the reinforced elongated bodies like an assembly of independent bars and which saves on antiabrasion materials as well
This can be accomplished by using an antiabrasion supporting mold which prevents wear on the bars. This type of antiabrasion protection is proposed in, for example, French Patent 2,494,401 and corresponding British Patent 2,088,320, wherein a mold groove serves as an antiabrasion lining. A supporting mold according to the invention made of an antiabrasion material makes it possible to reduce the quantity of material which is expensive because the thickness of the inside walls of the supporting element is less than the sum of the thicknesses of the adjacent walls of antiabrasion protection of two bars according to French Patent 2,494,401. The saving of material increases as the number of bars in a supporting element increases.
It is also possible to attach to the shape an element which acts as a lid to protect the bars against wear on their outer surfaces or open face of the supporting mold.
When a multi-rod shape is used, and especially when the multi-rod shape is antiabrasion in nature, the wear on the supporting mold and the bars should be distributed as much as possible and, for this purpose, one or more parts of one or more bars of the mold support may be joined by any suitable means.
The part or parts to be joined may be a vertical or horizontal surface or surfaces inside the supporting mold or may be a narrow zone of the vertical or horizontal surface which extends in a longitudinal direction. A vertical surface is a surface parallel to the radii of the circles osculant to the shape and the horizontal surface is a surface perpendicular at every point to the osculating radius passing through this point.
This could be accomplished, for example, by making integral with the supporting mold an entire bar near a center of the supporting mold, a single vertical surface near the center of the supporting mold, or several vertical surfaces not belonging to the same internal partition of the supporting mold, or the central zone of the bottom of one or more grooves in the supporting mold. This immobilizing surface or surfaces extend or extends longitudinally along the supporting mold, in a continuous or discontinuous manner.
The above-identified shape allows tight sheeting to be applied, and, is for this purpose it is sufficient for the edges of the supporting mold to be provided with recesses which, upon juxtaposition of two shapes of this type or of two consecutive turns of the same shape, would define a confined space which could be lined with an elastic material to provide tightness, adhering to the walls of this confined space and permitting considerable deformation.
Shapes to provide the sealing sheeting have already been described in, for example, French Patent 2,210,267 and corresponding U.S. Pat. No. 3,858,616.
Because of its width, the shape can also reduce the size of the confined spaces and the shape lends to stability to reinforcing sheeting on flexible pipe subjected primarily to flexion.
Since this phenomenon is particularly apparent when using flat bars, the effort exerted on the flexible material can allow bars not held by reinforcing sheeting to shift, causing harmful disorganization that could cause the flexible pipe to leak.
The proposed shape opposes this movement by means of grooves in the supporting mold which resist shifting of the bars and thus ensure improved stability of sheeting.
Like the self-locking bars mentioned in French Patent 2,210,267, the multi-bar shapes according to the invention can have lateral forms which permit self-locking of the shapes when two turns are adjacent.
The self-locking obtainable by the present invention is important to the stability of the reinforcing sheet among other things. The formation of the sealing sheeting such as, for example, sheeting resistant to pressure (tightness can be produced easily between complementary lateral shapes, for example, by gluing or applying an adhesive material), in the manufacture of pipe comprising only a single shaped sheet.
In the manufacture of reinforced hollow bodies, the shape may also have the base of the supporting mold pointing toward an interior of the hollow body rather than toward the outside.
When handling the multi-bar shape, it may be desirable for the bars to be held securely in the grooves of the supporting mold. This can be accomplished by immobilizing the bars, temporarily, for example, by gluing, and adjusting a degree of adhesion so that the bars will come loose from the supporting mold beyond a certain threshold of restraint.
To facilitate relative displacement of the bars with respect to one another, lubricating materials may be used which act immediately or only while the reinforced body is being used.
The invention provides a process for continuous manufacturing of shaped, bent, reinforcing bars with a constant or changing cross section or made of a reinforced stabilizable material, produced inside a shaped supporting mold, wound on a mandrel and containing reinforcing elements impregnated with stabilizable resin, before the stabilized resin is stabilized over at least a portion of the length of said mandrel. The supporting mold comprises several grooves in which the reinforcing elements, impregnated with stabilizable resin, thus produce simultaneously on the same mandrel, several curved bars with a shaped section made of reinforced stabilizable material.
Means may be provided for enabling the bars, once produced and placed in the supporting mold, to be relatively displaceable with respect to one another, and a one-piece supporting mold may be used to produce the bars.
The bars may be removed from the shaped supporting mold after stabilization, with the supporting mold being adapted for enabling separation of the shaped bars. Moreover, the shaped supporting mold could be continuously recycled once the bars are removed.
The stabilizable material comprising the bars could be caused to adhere to the inside wall of at least one groove in the supporting mold, or the stabilizable material may be formulated so as not to adhere to certain interior walls of the grooves in the support mold. Additionally, a shaped supporting mold may be used in an outside wall made of materials resistant to abrasion.
Additionally, a supporting mold may be used composed of two superimposed parts, with one part being separate from the other part after performing at least a partial stabilization of the resin in the curved bars.
After lining the grooves in the shaped supporting mold, the grooves may be covered with at least one element forming a lid, prior to stabilization and separated from the mandrel in the form of a unitized assembly including the entire shape, lining, and the element forming the lid. The element forming the lid may have a section adapted to allow the lid to fit onto the shaped supporting mold.
The invention also provides a shaped supporting mold for continuous manufacture of curved bars with a shaped cross section from a reinforced stabilized material produced inside this supporting mold in which the reinforcing elements impregnated with stabilizable resin are placed, with the supporting mold being wrapped around a mandrel and the resin being stabilized over at least a portion of the length of said mandrel This supporting mold may include several essentially parallel grooves with cross sections corresponding respectively to those of the various shaped bars to be simultaneously produced.
At least one groove of the supporting mold may have a height greater than a width thereof and may have edges adapted so that two adjacent helically wrapped turns can be hooked together. The invention also provides a process for continuously laying the reinforcing armatures of flexible elongated bodies, with the armatures being composed of several curved reinforcing bars.
According to the invention the laying machine is powered, with at least one unitized assembly composed of several bars grouped on a support, and the support is removed during the laying of the bars to form the armature. However, it is also possible to remove the bars before and during a laying of the reinforcing armature.
The support bars can be separated in a zone where the bars, pulled from the support or present in the support, are stretched. Moreover, the support bars may also be removed before the support bars constitute the reinforcing armature. Additionally, prior to feeding the unitized assembly to the laying machine, the support bars comprising the assembly may be placed on a support. Furthermore, once the support bars have been bent, the support bars may be grouped.
The invention also provides a device for continuously laying the reinforcing armatures of the flexible elongated bodies using at least one unitized assembly comprising several reinforcing bars grouped by a support with means being provided for permitting the reinforcing bars to be separated from the support. Of course, this operation is performed after eliminating the risk of tangling of the reinforcing bars with one another. This occurs primarily once the bars are laid on the elongated body or when the bars are placed in tension before being laid on the elongated body, or they are sufficiently close to the elongated body so they cannot tangle with one another.
The device of the present invention may comprise means for storing the support after using it for laying of the reinforcing armature, as well as means for storing and for supplying the unitized assembly for laying the bars. Additionally means for applying tension to the bars while they are being laid may be provided, with the tension applying means being operable at a level of the means for storing and supplying the unitized assembly. Furthermore, a bar-arranging grid may be provided for forming the armature.
The invention also provides a support for grouping the bars and keeping the bars aligned in a certain direction with the support comprising several separate elements.
The present invention also provides a flexible elongated body comprising at least.. one reinforced bent elongated shaped element, with reinforced bent elongated shaped element including a supporting element comprising several grooves essentially parallel to one another and extending along the longitudinal direction of the shaped element. At least two of the grooves each have one reinforcing bar, itself comprising filaments embedded in a stabilized material, and the supporting element is wrapped in a helix.
The bars may shift relative to one another as the flexible elongated body is used, and the shaped element may have at least one groove which has a height greater than a width thereof. Moreover, a base of the supporting element may be directed toward an interior of the elongated body, and the shaped element may comprise means for sliding at least one bar in the groove.
The shaped element may have a section adapted so that two adjacent turns of at least one of these shaped elements, wrapped helically, can delimit between the adjacent turns a confined space which may be filled by an adhesive elastic material.
Advantageously, according to the present invention, an element forming the lid may cover the supporting element lined with bars and form a unitized assembly with the shaped element. Additionally, the shaped element, possibly covered, may be composed of parts made of plastic. Moreover, the shaped element, possibly covered, may be composed of parts made of an abrasion-resistant material. Also a thickness of internal walls of the supporting element may be at most equal to a thickness of the outside walls of the supporting element.
The invention also provides a multi-bar shape comprising a supporting part with several grooves running essentially parallel to one another and extending in the longitudinal direction, with at least two, of the grooves each containing a reinforcing bar.
This multi-bar shape is characterized especially by the bars being adapted to shift relative to one another during use of said shaped element.
At least one bar can be made integral with the supporting element along one or more zones of a vertical or horizontal surface of a groove in the supporting element, with the zone or zones extending longitudinally in the supporting element in a continuous or discontinuous fashion.
The supporting mold may be adapted to serve as a support for the implementation of the laying process with recycling of the supporting mold or to serve as a supporting element for grouping the bars when assembling flexible elongated bodies.